Buried cables in concrete

I'd like to solicit some feedback on the experiences of members concerning direct burial of class 1 wiring in concrete. The United States has been addressed, and I am familiar with the requirements; however, information on the rest of the world eludes me. Responses from those familiar with Canada

wire size

Safety people, I would like to know what the standard wire sizes are in Europe, comparable to 12AWG, 14AWG, 16AWG, 18AWG solid. Would anyone across the pond be willing to assist on this. Or, anyone else that has the info. Thank you James Goedderz Product Safety Engineer Tyco Safety